Demonstrations by far right groups like the English Defence League (EDL) act like recruiting sergeants for Islamic militants across Britain, the head of a regional counter terrorism unit said on Friday.
Detective Superintendent John Larkin from West Midlands police said EDL marches and counter-demonstrations often ended in violence, with evidence they end up pushing some members of the community towards radicalisation.
"In some areas, we have evidence that once they have gone ... there's fertile ground for those groups (to say) 'this is the way white Western society sees us,'" he told BBC Radio.
"And that's a potential recruiting carrot for people and that's what some of these radicalisers look for -- they look for the vulnerability, for the hook to pull people through and when the EDL have been and done what they've done, they perversely leave that behind."
He said it was especially true if high-profile demos ended in the destruction of Muslim property or violence against community members.